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Re: fixup_mmaps_after_fork failure with cygwin-3.0.0

On Feb 17 00:11, Ken Brown wrote:
> I'm getting a lot of errors like this when building emacs from its git repo:
> EMACSLOADPATH= '../src/emacs.exe' -batch --no-site-file --no-site-lisp --eval 
> '(setq load-prefer-newer t)'  -f batch-byte-compile ../../master/lisp/finder.el
>        1 [main] emacs 26848 fixup_mmaps_after_fork: VirtualProtectEx failed for 
> MAP_PRIVATE address 0x6FFFFCD0000, Win32 error 5
>      190 [main] emacs 26848 C:\Users\kbrown\src\emacs\x86_64\src\emacs.exe: *** 
> fatal error in forked process - recreate_mmaps_after_fork_failed
>      619 [main] emacs 26848 cygwin_exception::open_stackdumpfile: Dumping stack 
> trace to emacs.exe.stackdump
>        1 [main] emacs 27052 fork: child -1 - forked process 26848 died 
> unexpectedly, retry 0, exit code 0x100, errno 11

Weird.  I built at least gawk and openssh with 3.0 already and I
didn't notice this problem.

> A bisection points to the following as the first bad commit:
> commit 69cc7a068656b5c6ef07ca079a213f801e02e650
> Author: Corinna Vinschen <corinna@xxxxxxxxxxx>
> Date:   Sun Jan 27 13:15:15 2019 +0100
>      Cygwin: fork: restrict parent handle perms and drop handle after use
> I'll try to do some debugging and/or provide further information tomorrow, but I 
> thought I'd start with this preliminary report.

That would be nice.  It's not clear to me which permission is missing.
The first part of the patch has been reverted in 3.0.0, so 
child_info_spawn::get_parent_handle opens the parent with
PROCESS_VM_READ again.  The second patch has been reworked as well,m
the current perms are


If I may place a bet, please try to replace

What OS is that?  W7?


Corinna Vinschen
Cygwin Maintainer

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